This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We have used cyo-EM and single particle analysis to determine structures of ion channels of the TRP family. Those studied included TRPV1, the receptor for painful heat that also senses the active ingredient in hot chili peppers, capsaicin, TRPV2, another heat sensor, and TRPY1, an ion channel of the yeast vacuole that releases calcium into the cytoplasm in response to osmotic stress. We have also used cryo-EM to characterize vesicles into which TRP channels been reconstituted, which allowed us to quantify the activity of the reconstituted channels. The TRP family of non-selective cation channels represent one of the most important classes of ion channels for human physiology, and constitutes a major class of drug targets. Our work represents the first reliable three-dimensional structural information available for any full-length TRP chanels, and also the first quantitative assays of purified and reconstituted TRP channels.